CD11b is involved in various adhesive interactions of monocytes, macrophages and granulocytes as well as in mediating the uptake of complement-coated particles. CD11b is identical with CR-3, the receptor for the iC3b fragment of the third complement component. Genetic variations in CD11b have been associated with susceptibility to systemic lupus erythematosus type 6 (SLEB6). SLEB6 is a chronic, inflammatory and often febrile multisystemic disorder of connective tissue. It affects principally the skin, joints, kidneys and serosal membranes. It is thought to represent a failure of the regulatory mechanisms of the autoimmune system.